People in 17 states found themselves unable to buy groceries with their food stamp debit-style cards Saturday after a routine check by vendor Xerox Corp. resulted in a system failure.

Xerox announced late in the evening that access had been restored for users in the 17 states affected by the outage, hours after the first problems were reported.

"Re-starting the EBT system required time to ensure service was back at full functionality," spokeswoman Jennifer Wasmer said in an email.

Xerox spokeswoman Karen Arena told USA TODAY that some Electronic Benefits Transfer systems were experiencing connectivity issues after a routine test of a backup system at a location in the Midwest caused an outage at about 10 a.m. ET. The test was part of a regular maintenance schedule, Arena said.

Xerox started receiving calls soon afterward.

U.S. Department of Agriculture spokeswoman Courtney Rowe underscored that the outage was not related to the federal government shutdown. Xerox runs EBT card systems for 17 states. All were affected by the outage.

Ohio's cash and food assistance card payment systems went down at 11 a.m., said Benjamin Johnson, a spokesman for the Ohio Department of Job and Family Services.

Shoppers left carts of groceries behind at a packed Market Basket grocery store in Biddeford, Maine, because they couldn't get their benefits, said fellow shopper Barbara Colman, of Saco, Maine. The manager put up a sign saying the EBT system was not in use. Colman, who receives the benefits, called an 800 telephone line for the program and it said the system was down due to maintenance, she said.

"That's a problem. There's a lot of families who are not going to be able to feed children because the system is being maintenanced," Colman said. "No one should put maintenance in during the daytime."

She planned to reach out to local officials.

"I'm trying to reach out to everybody because I'm not thinking of me an adult who can figure out things. I'm thinking of the simpler person in the world who is sitting there trying to just do basic shopping to feed their kids. You don't want children going hungry tonight because of stupidity," she said.

Colman said the store manager promised her that he would honor the day's store flyer discounts next week.

Illinois residents began reporting problems with their cards — known as LINK in that state — on Saturday morning, said Januari Smith, spokeswoman for the Illinois Department of Human Services.

Smith said that typically when the cards aren't working retailers can call a backup phone number to find out how much money a customer has available in their account. But that information also was unavailable because of the outage, so customers weren't able to use their cards.

In Clarksdale, Miss. — one of the poorest parts of one of the poorest states in the nation — cashier Eliza Shook said dozens of customers at Corner Grocery had to put back groceries when the cards failed Saturday because they couldn't afford to pay for the food. After several hours, she put a sign on the front door to tell people about the problem.

"It's been terrible," Shook said in a phone interview. "It's just been some angry folks. That's what a lot of folks depend on."

Mississippi Department of Human Services director Rickey Berry confirmed that Xerox, the state's EBT vendor, had computer problems. He said he had been told by midafternoon that the problems were being fixed.

"I know there are a lot of mad people," Berry said.

Sheree Powell, a spokeswoman for the Oklahoma Department of Human Services, started receiving calls around 11:30 a.m. about problems with the state's card systems. More than 600,000 Oklahomans receive SNAP benefits, and money is dispersed to the cards on the first, fifth and 10th days of every month, so the disruption came at what is typically a high-use time for the cards.

Oklahoma also runs a separate debit card system for other state benefits like unemployment payments. Those cards can be used at ATMs to withdraw cash. Powell said Xerox administers both the EBT and debit card systems, and they both were down initially.

Like Ohio's Johnson, Powell said that Oklahoma's cash debit card system has since been restored, but the EBT cards for the SNAP program were still down. Powell said Oklahoma's Xerox representative told them that the problems stemmed from a power failure at a data center, and power had been restored quickly.

"It just takes a while to reboot these systems," she said, adding that she did not know where the data center was located.

Powell said that some grocery store cashiers had been speculating that the federal government's shutdown caused the problem, but state officials have been assured that that is not the case.

"We are hopeful it will be up this afternoon but we were not given a specific time frame," she said.

David Akerly, a spokesman for Michigan's Department of Human Services, also confirmed that residents in his state have reported problems using their cards.